An Apple patent reveals next-gen Ultrasonic Temperature Sensors for Apple Watch & iPhone for measuring Air and Water Temperatures
Apple's first generation of temperature sensors on Apple watch were focused on tracking a woman's ovulation cycle. Today the U.S. Patent Office published a patent application from Apple that relates to new ultrasonic temperature sensors that provides ambient temperature of the air, or the temperature of another environmental medium such as water, other fluids or other material outside the electronic device, such as glass.
Electronic Devices With Ultrasonic Temperature Sensors
Apple notes that electronic devices are often carried by users as they conduct their daily activities. For example, a user may carry an electronic device on their person throughout the day while walking, commuting, working, exercising, etc. In some situations, it may be desirable for the user to know the ambient temperature of the air, or the temperature of another environmental medium (e.g., water).
Although electronic devices may receive information regarding ambient temperature and weather conditions through various online resources, this information may not be accurate for the user's exact location, such as shaded areas (e.g., under a tree or on a shaded trail) or on surfaces that may affect the ambient temperature (e.g., grass or asphalt). Therefore, one or more temperature sensors may be incorporated into the electronic devices to measure environmental temperature directly.
The temperature sensors may be ultrasonic temperature sensors that determine the speed of sound through the ambient air (or through another surrounding medium). The speed of sound may then be used to determine the temperature of the air or other surrounding medium. In this way, temperature sensors within an electronic device may make accurate temperature measurements of the environment surrounding the user.
The temperature sensor may be formed in a cavity or opening within the housing, and may be covered with a mesh or grille, if desired. The temperature sensor may include any desired number of transmitters and receivers (e.g., arrays of PMUTs), and may have dedicated ultrasonic transmitters and receivers or may have PMUTS that both transmit and receive ultrasonic signals. Each PMUT may be formed on a complementary metal-oxide semiconductor (CMOS).
The Apple Watch and iPhone will be the main targets for this next-gen ultrasonic temperature sensor as noted in patent FIGS. 1 and 2; FIG. 3 is a diagram of an illustrative electronic device that includes temperature sensors; FIG. 5 is a graph of an illustrative relationship between temperature and a measured speed of sound.
Apple's patent FIG. 6 above is a graph of an illustrative relationship between air density/atmospheric pressure and altitude; FIG. 11 is a top view of an illustrative array of piezoelectric micromachined ultrasonic transducers that may be used in an ultrasonic temperature sensor.
For full details, review Apple's patent application 20240019318.
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